Am I upset for no reason ?

So my boyfriend graduated yesterday and as I’m watching the video I noticed he was holding a girls hand down the aisle. I spoke to him about the ceremony and he mentioned nothing of it. I then mention it to him and he asked me “who Jane? “ and he proceeded to say that the girl said she was “scared “ and asked to hold his hand . I thought “awww w so sweet “ & how nice of a gentleman he was . He kept asking how did I know but im sure he knew there were literally cameras every where . But I can’t help but feel some type of way. Why didn’t he tell me ? I need some advice to get over how i feel .